Low glycemic index vegan or low-calorie weight loss diets for women with polycystic ovary syndrome: a randomized controlled feasibility study

The Influence of Dietary Patterns on Polycystic Ovary Syndrome Management in Women: A Review of Randomized Controlled Trials with and Without an Isocaloric Dietary Design

Polycystic ovary syndrome (PCOS) is an endocrine disorder that causes cardiometabolic and reproductive disorders in women of reproductive age. Women with PCOS are more likely to have obesity, type 2 diabetes mellitus, and cardiovascular disease. There is an inconclusive consensus on which dietary modification could be most effective in PCOS prevention and treatment. This review aimed to examine the effects of diverse dietary patterns on PCOS in women according to randomized controlled trials (RCTs) with and without an isocaloric dietary design. A literature search was performed in the PubMed®®/MEDLINE®® database up to 14 November 2024. A total of 21 RCTs were reviewed after screening the records, including 15 RCTs with a calorie-restricted dietary design and 6 RCTs with a non-calorie-restricted dietary design. This review found beneficial effects of the calorie-restricted Dietary Approaches to Stop Hypertension (DASH) diet on weight loss and glucose control in women with PCOS in four RCTs with an isocaloric dietary design. The calorie-restricted low-glycemic index (GI) diets from three RCTs and high-protein diets from four RCTs with an isocaloric dietary design showed no significant differences in anthropometric parameters, glucose control, lipids, and gonadal parameters compared with the control diet in women with PCOS. Non-calorie-restricted low-carbohydrate diets from four RCTs with an isocaloric dietary design showed similar results to the calorie-restricted low-GI diets and high-protein diets. However, the existing number of RCTs is insufficient to conclude the association between dietary patterns and PCOS in women. Further, well-designed dietary intervention studies are needed to assess the role of dietary patterns in PCOS beyond calorie restriction.

The effects of portfolio moderate-carbohydrate and ketogenic diets on anthropometric indices, metabolic status, and hormonal levels in overweight or obese women with polycystic ovary syndrome: a randomized controlled trial

BACKGROUND

Polycystic Ovary Syndrome (PCOS) is one of the most common hormonal disorders in reproductive-age women caused by hyperinsulinemia. The portfolio Moderate-carbohydrate diet (PMCD) is a plant-based diet with a carbohydrate content of 40% and incorporates five cholesterol-lowering foods. While, the ketogenic diet is a high-fat diet with 70% fat, promoting a ketosis state. To the best of our knowledge, no study compared the therapeutic effects of these two diets in PCOS patients. Thus, this study aimed to compare the impact of PLCD and KD on anthropometric indices, metabolic status, and hormonal levels in overweight or obese women with PCOS.

METHODS

This open-label, randomized clinical trial was conducted on forty-six PCOS women. 21 women in PMCD and 19 in the KD group completed the study. The anthropometric indices including body mass index (BMI) and fat body mass (FBM), metabolic markers (fasting blood glucose (FBG)) and plasma lipid profiles including low-density lipoprotein (LDL), triglycerides, and high-density lipoproteins (HDL) were measured. Reproductive hormones such as luteinizing hormone (LH), dehydroepiandrosterone sulfate (DHEA-s) and free testosterone were assessed at the baseline and after the intervention.

RESULTS

However, after 8 weeks both diets demonstrated enhancement in anthropometric indices (BMI, FBM, lean body mass), metabolic status (FBG, insulin serum levels), and reproductive hormones such as LH, free testosterone, and DHEA-s. The mean difference in the KD improved more than the PMCD in the field of BMI reduction (MD (SD) 2.73 (0.351) vs. MD (SD) 1.71 (0.775)) and LH (MD 4.13 (1.375) vs.MD 2.46 (1.105)). Nevertheless, the lipid profile including LDL-C and triglycerides improved more in the PMCD compared to the KD (MD 33.95 (7.345) vs. MD 23.34 (14.136)) and (MD 38.20 (10.757) vs. MD 57.62 (21.688)) respectively. There were no significant changes in the Ferriman-Gallwey score within or between the two groups.

CONCLUSION

The findings revealed that both diets were effective in improving PCOS manifestations. However, the KD exhibited greater effectiveness in enhancing body measurements, metabolic factors, and reproductive hormone levels compared to the PMCD in obese PCOS women. Furthermore, PMCD could be more beneficial for PCOS women with lipide disorders.

REGISTRATION NUMBER OF CLINICAL TRIAL

IRCT20200912048693N3, Trial registered 2022-12-14. https://www.irct.ir/trial/67548.

Ranking the dietary interventions by their effectiveness in the management of polycystic ovary syndrome: a systematic review and network meta-analysis

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a common condition in women, characterised by reproductive and metabolic dysfunction. While dietary approaches have been evaluated as a first-line treatment for patients with PCOS, there is limited evidence to support preference for a specific dietary composition. This systematic review and network meta-analysis was performed with the objective of comparing different dietary interventions in terms of positive impact. Metformin, the currently preferred treatment, was also compared.

METHODS

The latest systematic search was performed on the 20th of March, 2023. Eligible randomised controlled trials (RCTs) included patients with PCOS and compared the dietary approach with another intervention or a standard diet. Outcomes were expressed via anthropometric measurements and hormonal, glycemic, and lipid levels. The Bayesian method was used to perform a network meta-analysis and to calculate the surface under the cumulative ranking curve (SUCRA) values in order to rank the dietary interventions. The overall quality of the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation system.

RESULTS

19 RCTs were identified, comprising data from 727 patients who were variously treated with 10 types of dietary interventions and metformin. The Dietary Approaches to Stop Hypertension (DASH) diet was the most effective in reducing Homeostatic Model Assessment of Insulin Resistance (SUCRA 92.33%), fasting blood glucose (SUCRA 85.92%), fasting insulin level (SUCRA 79.73%) and triglyceride level (SUCRA 82.07%). For body mass index (BMI), the most effective intervention was the low-calorie diet (SUCRA 84.59%). For weight loss, the low-calorie diet with metformin (SUCRA 74.38%) was the most effective intervention. Metformin produced the greatest reductions in low-density lipoprotein cholesterol (SUCRA 78.08%) and total testosterone levels (SUCRA 71.28%). The low-carb diet was the most effective intervention for reducing cholesterol levels (SUCRA 69.68%), while the normal diet (SUCRA 65.69%) ranked first for increasing high-density lipoprotein cholesterol levels.

CONCLUSION

Dietary interventions vary in their effects on metabolic parameters in women with PCOS. Based on our results, the DASH diet is the most effective dietary intervention for treating PCOS. Registration PROSPERO ID CRD42021282984.

The Effect of a Very-Low-Calorie Diet (VLCD) vs. a Moderate Energy Deficit Diet in Obese Women with Polycystic Ovary Syndrome (PCOS)-A Randomised Controlled Trial

We performed an open-label, randomised controlled trial to compare the effects of a very-low-calorie diet (VLCD) vs. moderate energy deficit approach on body weight, body composition, free androgen index (FAI), and metabolic markers in obese women with polycystic ovary syndrome (PCOS). Forty eligible patients were randomly assigned to a VLCD (n = 21) or a conventional energy deficit approach (n = 19) over the same period. After eight weeks, both groups experienced significant weight loss; however, this was greater in the VLCD arm (-10.9% vs. -3.9%, p < 0.0001). There was also a trend towards a reduction in FAI in the VLCD group compared to the energy deficit group (-32.3% vs. -7.7%, p = 0.07). In the VLCD arm, two women (18%) had a biochemical remission of PCOS (FAI < 4); this was not the case for any of the participants in the energy deficit arm. There was a significant within-group increase in the sex-hormone-binding globulin (p = 0.002) and reductions in fasting blood glucose (p = 0.010) and waist to hip ratio (p = 0.04) in the VLCD arm, but not in the energy deficit arm. The VLCD resulted in significantly greater weight reduction and was accompanied by more pronounced improvements in hyperandrogenaemia, body composition, and several metabolic parameters in obese women with PCOS as compared to the energy deficit approach.

Glycemic Index and Glycemic Load Estimates in the Dietary Approach of Polycystic Ovary Syndrome

Polycystic ovary syndrome is a common endocrine disorder characterized by hormonal imbalances and various metabolic abnormalities linked to insulin resistance via a vicious cycle. Genetic and environmental factors underlie its pathogenesis and evolution. Nutrition, in terms of nutrient composition, dietary patterns, endocrine-disrupting chemicals, and food processing and preparation, has gained significant attention in the pathogenesis and the therapeutic approach of polycystic ovary syndrome. Carbohydrate intake seems to be a critical point in the diet assignment. Glycemic index and glycemic load constitute indexes of the impacts of dietary carbohydrates on postprandial glucose levels. Numerous studies have indicated that a high glycemic index and glycemic load diet may exacerbate insulin resistance, a key feature of the syndrome, and offer a risk for its development and its complications. Conversely, low-glycemic index and low-glycemic load diets seem to improve insulin sensitivity, regulate menstrual cycles, and mitigate the risk of comorbidities associated with polycystic ovary syndrome, such as obesity, alterations in body composition, type 2 diabetes, cardiovascular disease, and quality of life. This comprehensive review aims to explore the relevance of nutrition and more specifically, the association of glycemic index and glycemic load with the various aspects of polycystic ovary syndrome, as well as to assess the potential benefits of manipulating those indexes in the dietary approach for the syndrome.

Lifestyle management in polycystic ovary syndrome - beyond diet and physical activity

Polycystic ovary syndrome (PCOS) is a common condition affecting reproductive-aged women with reproductive, metabolic and psychological consequences. Weight and lifestyle (diet, physical activity and behavioural) management are first-line therapy in international evidence-based guidelines for PCOS. While these recommend following population-level diet and physical activity guidelines, there is ongoing interest and research in the potential benefit of including psychological and sleep interventions, as well as a range of traditional, complimentary and integrative medicine (TCIM) approaches, for optimal management of PCOS. There is limited evidence to recommend a specific diet composition for PCOS with approaches including modifying protein, carbohydrate or fat quality or quantity generally having similar effects on the presentations of PCOS. With regards to physical activity, promising evidence supports the provision of vigorous aerobic exercise, which has been shown to improve body composition, cardiorespiratory fitness and insulin resistance. Psychological and sleep interventions are also important considerations, with women displaying poor emotional wellbeing and higher rates of clinical and subclinical sleep disturbance, potentially limiting their ability to make positive lifestyle change. While optimising sleep and emotional wellbeing may aid symptom management in PCOS, research exploring the efficacy of clinical interventions is lacking. Uptake of TCIM approaches, in particular supplement and herbal medicine use, by women with PCOS is growing. However, there is currently insufficient evidence to support integration into routine clinical practice. Research investigating inositol supplementation have produced the most promising findings, showing improved metabolic profiles and reduced hyperandrogenism. Findings for other supplements, herbal medicines, acupuncture and yoga is so far inconsistent, and to reduce heterogeneity more research in specific PCOS populations, (e.g. defined age and BMI ranges) and consistent approaches to intervention delivery, duration and comparators are needed. While there are a range of lifestyle components in addition to population-recommendations for diet and physical activity of potential benefit in PCOS, robust clinical trials are warranted to expand the relatively limited evidence-base regarding holistic lifestyle management. With consumer interest in holistic healthcare rising, healthcare providers will be required to broaden their knowledge pertaining to how these therapies can be safely and appropriately utilised as adjuncts to conventional medical management.

Altered Molecular Pathways and Biomarkers of Endometrial Receptivity in Infertile Women with Polycystic Ovary Syndrome

Anovulation is the most prominent cause of infertility in polycystic ovary syndrome (PCOS) patients. Although ovulation can be corrected pharmacologically, the number of pregnancies remains low. Even if excellent embryos are transferred by IVF, it does not change the high miscarriage rate of PCOS patients. These facts collectively indicate that there is a disorder of endometrial development and receptivity to the embryo in PCOS patients, including the decrease of receptive ability, inhibition of embryo adhesion, undersupply of energy, poor blood perfusion, and pro-inflammatory status in the endometrium. However, it has never received the same attention as ovulatory dysfunction. Here we list some alternations of endometrial receptivity in women with PCOS, discuss the underlying intricate mechanisms, and try to find out the possible therapeutic targets, which may bring new perspectives to those who are able to provide high-quality embryos.

An overview on effects of micronutrients and macronutrients interventions in management of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the common endocrinopathies among women. Changing dietary behaviors for PCOS management has been an important research focus during the last decades. This review has discussed current evidence and clinical trial studies relating to the impact of macronutrients and micronutrients in the management of different clinical feature of PCOS. The possible relationship between the quality and quantity of micronutrients and macronutrients and PCOS as well as the necessity to manage PCOS as a complex condition highlights the importance of diet-related interventions. The growing number of clinical trials related to the effect of micronutrients (zinc, chromium, selenium, vitamin D, inositol, and vitamin E) and macronutrients interventions (manipulation of fat, carbohydrate, protein, and MedDiet, Calorie restriction, Low Glycemic Diet) have been demonstrated to be practical approaches for managing clinical and biochemical features of PCOS, however the potential benefit of micronutrient and macronutrient approaches could be different from one by one, particularly in different phenotypes of PCOS. To achieve optimum outcomes, providing information regarding safety and the best dose selection of micronutrients and macronutrients is necessary. Hence, to better understand the approaches' risk/benefit in women with PCOS, future trials with a large sample size are recommended.

Comparison of dietary and physical activity behaviors in women with and without polycystic ovary syndrome: a systematic review and meta-analysis of 39 471 women

BACKGROUND

Lifestyle (dietary and/or physical activity [PA]) modification is recommended as first-line therapy to manage polycystic ovary syndrome (PCOS). Current recommendations are based on healthy lifestyle practices for the general public since evidence for unique lifestyle approaches in PCOS is limited and low quality.

OBJECTIVE AND RATIONALE

We aimed to synthesize evidence on dietary and PA behaviors between women with PCOS and those without PCOS. Primary outcomes were overall diet quality, total energy intake and total PA, and secondary outcomes included macronutrients, micronutrients, food groups, foods, glycemic indices, sedentary time and sitting levels. We conducted this work to identify any unique lifestyle behaviors in women with PCOS that could underlie the propensity of weight gain and obesity in PCOS and be targeted for precision nutrition and PA interventions. These findings could be used to inform future practice recommendations and research that more effectively address complications (weight gain, obesity, diabetes, infertility, cardiovascular disease and mental health) in this high-risk population.

SEARCH METHODS

Databases of MEDLINE, Web of Science, Scopus and CINAHL were searched until 15 February 2022 to identify observational studies documenting dietary and PA behaviors between women with PCOS and without PCOS (Controls). Studies on children, adolescents (<18 years), pregnant or menopausal-aged women (>50 years) were excluded. Data were pooled by random-effects models and expressed as (standardized) mean differences (MD) and 95% CIs. The risk of bias was assessed by the Newcastle-Ottawa scale (NOS).

OUTCOMES

Fifty-four studies (N = 39 471 participants; [n = 8736 PCOS; 30 735 Controls]) were eligible (96%; [52/54] NOS scores ≥ 7). Women with PCOS had higher cholesterol (MD: 12.78, 95% CI: 1.48 to 24.08 mg/day; P = 0.03; I2 = 19%), lower magnesium (MD: -21.46, 95% CI: -41.03 to -1.91 mg/day; P = 0.03; I2 = 76%), and a tendency for lower zinc (MD: -1.08, 95% CI: -2.19 to -0.03 mg/day; P = 0.05; I2 = 96%) intake, despite lower alcohol consumption (MD: -0.95, 95% CI: -1.67 to 0.22 g/day; P = 0.02; I2 = 0%) versus Controls. Also, women with PCOS had lower total PA (standardized mean difference: -0.38, 95% CI: -0.72 to 0.03; P = 0.03; I2 = 98%). Conversely, energy, macronutrients (carbohydrate, fat, protein, fiber), micronutrients (folic acid, iron, calcium, sodium), glycemic index and glycemic load were similar (all: P ≥ 0.06). Most eligible studies reported lower total adherence to healthy eating patterns or poorer consumption of major food groups (grains, fruits, vegetables, proteins, seeds, nuts, dairy) in women with PCOS, as described narratively since variable study methodology did not permit meta-analyses.

WIDER IMPLICATIONS

Collective evidence supports that women with PCOS have a lower overall diet quality, poorer dietary intakes (higher cholesterol, lower magnesium and zinc) and lower total PA, despite lower alcohol consumption versus those without PCOS. Considerable heterogeneity among studies reinforces the need for research to address any relative contributions of other factors (e.g. genetic, metabolic or sociodemographic) to the observed differences. These clarifications may contribute to future evidence-based guideline recommendations on monitoring and managing PCOS in the era of precision lifestyle medicine.

Process evaluation methods and results from the Health in Pregnancy and Postpartum (HIPP) randomized controlled trial

Background

Excessive gestational weight gain has increased over time and is resistant to intervention, especially in women living with overweight or obesity. This study described the process evaluation methods and findings from a behavioral lifestyle intervention for African American and white women living with overweight and obesity that spanned pregnancy (≤ 16 weeks gestation) through 6 months postpartum.

Methods

The Health in Pregnancy and Postpartum (HIPP) study tested a theory-based behavioral intervention (vs. standard care) to help women (N = 219; 44% African American, 29.1 ± 4.8 years) living with overweight or obesity meet weight gain guidelines in pregnancy and lose weight in postpartum. Participants completed process evaluation surveys at 32 weeks gestation (n = 183) and 6 months postpartum (n = 168) regarding their perceptions of most and least helpful aspects of the intervention. A database tracked delivery and receipt of intervention components (in-depth counseling session, telephone calls, podcasts). Descriptive statistics are used to report fidelity, dose, and participants’ perceptions. We also tested whether dose of behavioral intervention components was associated with gestational weight gain and 6-month postpartum weight retention with linear regression models controlling for baseline age and gestational weeks, receipt of Medicaid, race, parity, and marital status. A content analysis was used to code and analyze responses to open-ended survey questions.

Results

Over 90% of participants (both groups) would recommend the program to a friend. Implementation fidelity was moderately high and greater in pregnancy than postpartum for all intervention components. Dose received and participants’ ratings of the in-depth counseling session and telephone calls were more favorable than podcasts. The Facebook group was not perceived to be very helpful, likely because of low participant interaction. Although podcasts were created to reinforce call topics, this redundancy was viewed negatively by some. More calls completed and more podcasts downloaded related to lower gestational weight gain (p < .05).

Conclusion

Study findings underscore challenges in engaging this important but busy population, especially during the postpartum period.

Trial registration:

The study was registered at clinicaltrials.gov (NCT02260518) on 10/09/2014. https://clinicaltrials.gov/ct2/show/NCT02260518.

Plant-Based Dietary Patterns for Human and Planetary Health

The coronavirus pandemic has acted as a reset on global economies, providing us with the opportunity to build back greener and ensure global warming does not surpass 1.5 °C. It is time for developed nations to commit to red meat reduction targets and shift to plant-based dietary patterns. Transitioning to plant-based diets (PBDs) has the potential to reduce diet-related land use by 76%, diet-related greenhouse gas emissions by 49%, eutrophication by 49%, and green and blue water use by 21% and 14%, respectively, whilst garnering substantial health co-benefits. An extensive body of data from prospective cohort studies and controlled trials supports the implementation of PBDs for obesity and chronic disease prevention. The consumption of diets high in fruits, vegetables, legumes, whole grains, nuts, fish, and unsaturated vegetable oils, and low in animal products, refined grains, and added sugars are associated with a lower risk of all-cause mortality. Meat appreciation, health concerns, convenience, and expense are prominent barriers to PBDs. Strategic policy action is required to overcome these barriers and promote the implementation of healthy and sustainable PBDs.

The Effect of Exercise Training on Body Composition, Insulin Resistance and High Sensitivity C-reactive Protein (Hs-CRP) in Women With Polycystic Ovary Syndrome: A Pilot Study From North India

Background

Polycystic ovary syndrome (PCOS) is defined as clinical or biochemical hyperandrogenism, oligo/amenorrhea, and polycystic ovaries with or without increased ovarian volume. The goal of this study was to assess the effect of a 20-week home-based aerobic exercise programme on body composition, insulin resistance, and hs-CRP levels in women with PCOS.

Methods

This 12-month prospective study included 60 female patients diagnosed with PCOS, aged 20 to 40 years. The participants were divided into 2 groups, one for the experiment and the other for the control. For each participant, the 12-hour fasting blood samples were taken on two occasions i.e., 24 hours before the first session and 48 hours after the last session to measure the fasting glucose, fasting insulin, and hs-CRP. The Statistical Package for Social Sciences (SPSS) was used to conduct the analysis, and an association was considered significant when the p-value was less than 0.05.

Results

In the present study, there was a dropout rate of 16.7% (5/30) in the study group and 23.3% (7/30) in the control group. The baseline characteristics were comparable (p>0.05) between the study group and the control group during the enrolment. The BMI (kg/m²) among the study group before the exercise programme was 22.8±1.8 and it was significantly reduced to 21.1±1.9 after the exercise programme (p<0.05). The HOMA-IR and hs-CRP (mg/L) levels among the study group before the exercise programme were 3.2±1.5 and 6.7±2.7 respectively, and these were significantly reduced to 1.9±1.6 and 4.2±1.3 respectively after the exercise programme (p<0.05). In contrast, paired T-test analysis showed no such significant difference (p<0.05) for all variables (Weight, BMI, Waist, Hip, fasting glucose, Fasting insulin, and hs-CRP) among the control group during the study period.

Conclusion

In a group of female PCOS patients, a 20-week home-based aerobic exercise programme reduced weight, BMI, HOMA-IR, and hs-CRP. Although more research on the effects of aerobic exercises in PCOS is needed, these findings support aerobic exercise's effectiveness in reducing inflammation and enhancing insulin sensitivity in these patients.

Beyond Calorie Tracking: A Pilot Trial of a Remotely Delivered Behavioral Weight Loss Intervention Using an Ad Libitum Plant-Based Diet (Preprint)

Background

Many traditional lifestyle interventions use calorie prescriptions, but most individuals have difficulty sustaining calorie tracking and thus weight loss. In contrast, whole food plant-based diets (WFPBDs) have previously shown significant weight loss without this issue. However, most WFPBD interventions are face-to-face and time-intensive, and do not leverage gold standard behavioral strategies for health behavior change.

Objective

This open pilot trial was the first to evaluate the feasibility of a fully featured, remotely delivered behavioral weight loss intervention using an ad libitum WFPBD.

Methods

Over 12 weeks, participants (N=15) with overweight or obesity received a newly designed program that integrated behavioral weight loss and a WFPBD prescription via weekly web-based modules and brief phone coaching calls. Assessments were performed at baseline, midtreatment (6 weeks), and after treatment (12 weeks).

Results

The intervention was rated as highly acceptable (mean 4.40 out of 5, SE 0.18), and attrition was low (6.7%). In all, intention-to-treat analyses revealed that 69% (10.4/15) of the participants lost 5% of their weight (mean –5.89, SE 0.68 kg). Predefined benchmarks for quality of life were met.

Conclusions

A pilot digital behavioral weight loss intervention with a non–energy-restricted WFPBD was feasible, and the mean acceptability was high. Minimal contact time (80-150 minutes of study interventionist time per participant over 12 weeks) led to clinically relevant weight loss and dietary adherence for most participants (10.4/15, 69% and 11.8/15, 79%, respectively), and quality of life improvements (reliable change indices >1.53). We hope that this work will serve as a springboard for future larger scale randomized controlled studies evaluating the efficacy of such programs for weight loss, dietary change, and quality of life.

Trial Registration

ClinicalTrials.gov NCT04892030; https://clinicaltrials.gov/ct2/show/NCT04892030

Plant-Based Diet as a Strategy for Weight Control

According to the World Health Organization, obesity has nearly tripled since the 1970s. Obesity and overweight are major risk factors for cardiovascular diseases, diabetes, inflammatory-mediated diseases, and other serious medical conditions. Moreover, recent data suggest that obesity, overweight, diabetes, and cardiovascular diseases are risk factors for COVID-19-related mortality. Different strategies for weight control have been introduced over the last two decades. Unfortunately, these strategies have shown little effect. At the same time, many studies show that plants might be the key to a successful strategy for weight control. Following the PRISMA guidelines for conducting systematic reviews, a search was conducted in PubMed, Web of Science, Scopus, and Embase using the following keywords: obesity, globesity, vegan, plant-based diet, etc. Our results show that vegan diets are associated with improved gut microbiota symbiosis, increased insulin sensitivity, activation of peroxisome proliferator-activated receptors, and over-expression of mitochondrial uncoupling proteins. The key features of this diet are reduced calorie density and reduced cholesterol intake. The combination of these two factors is the essence of the efficiency of this approach to weight control. Our data suggest that plant-based/vegan diets might play a significant role in future strategies for reducing body weight.

The effect of low glycemic index diet on the reproductive and clinical profile in women with polycystic ovarian syndrome: A systematic review and meta-analysis

Background

Treatment for polycystic ovary syndrome (PCOS) usually initiates with a series of lifestyle modifications such as diet, weight loss, and exercise.

Aims

We, therefore, conducted this meta-analysis to systematically review and evaluate the possible benefits of LGD on a range of anthropometric, clinical, and biochemical parameters in women with PCOS.

Methods

We performed a systematic search through major indexing databases, including Scopus, Pubmed/Medline, ISI web of science, Embase, Cochrane central, and CINAHL (1966-April 30, 2021) using key concepts of PCOS.

Results

Of 935 initial publications, 542 remain after duplicates removal. Then, 141 records were removed at the title and abstract screening level. After excluding 392 literatures, we finally included 8 articles. The final selected studies included 412 overweight and obese individuals with PCOS (207 cases in LGID group and 205 patients in comparators) with a mean age of 21-32 years. Measured emotional health (3 studies, 132 participants, SMD: -1.97; 95%CI:-3.54, -0.40, P = 0.01, I ² = 89%) and body hair (3 studies, 132 participants, SMD: -0.40; 95%CI:-0.46, -0.35, P < 0.0001, I ² = 0%), were found to be significantly lower in women in LGD vs control diet groups. Moreover, infertility (3 studies, 132 participants, SMD: 1.45; 95%CI: 0.30, 2.61, P = 0.01, I ² = 79%) was significantly higher in women in LGD vs control diet groups.

Conclusion

The present meta-analysis has shown that LGD may play a significant role in reducing the risk and improving the clinical and biochemical features of PCOS. So far the evidences for choosing the best dietary modalities for PCOS are not strong to make a definite recommendation.

Plant-predominant eating patterns - how effective are they for treating obesity and related cardiometabolic health outcomes? - a systematic review

CONTEXT

The obesity epidemic is a main driver of the chronic disease epidemic; however, present treatment approaches have suboptimal efficacy.

OBJECTIVES

To assess the efficacy of plant-predominant (vegan, vegetarian, plant-based whole foods [PBWFs]) diets in treating obesity and its main cardiometabolic sequelae: hyperlipidemia (HLD); indices of insulin resistance, glycemic control, and diabetes mellitus type 2 (DM2); and cardiovascular disease (CVD), including hypertension (HTN).

DATA SOURCES

A systematic search of multiple databases was conducted for articles published between November 2019 and February 2020; databases searched included: PubMed, Medline (Ovid), Cochrane, CENTRAL, and CINAHL.

DATA EXTRACTION AND ANALYSIS

All interventional trials (randomized controlled trials [RCTs] and trials of non-randomized experimental design) that met the inclusion criteria (English language, duration of at least 4 weeks, primary end point congruent with above objectives, no major flaws in research design that would prevent interpretation) were included in the review. A total of 3135 articles were scanned and 84 were selected. The articles were collated and summarized in 2 evidence tables. Risk of bias for RCTs was assessed using the Cochrane Risk-of-Bias tool 2 as a guide. For non-randomized trials, higher risk of bias was assumed, and the JBI Critical Appraisal tool was used as a guide to determine inclusion.

RESULTS

Plant-based diets, in general, demonstrated improved weight control and cardiometabolic outcomes related to lipids, cardiovascular end points, blood pressure, insulin sensitivity, A1C, and fasting glucose, and a lower risk of diabetes compared with usual diets and in some cases standard health-oriented diets such as the American Heart Association (AHA), American Diabetic Association (ADA), and Mediterranean diets. Preliminary studies suggest plant-predominant diets practiced as part of healthy lifestyle interventions may stabilize or even reverse DM 2 and CVD. The acceptability and sustainability of plant-predominant diets where measured were generally similar to other health-oriented diets.

CONCLUSION

Plant-predominant diets can play a major role in reversing the obesity and chronic disease epidemics. In the setting of sustained lifestyle intervention programs, they may arrest or even reverse DM2 and CVD. Further higher-level RCTs are needed to confirm and expand on these findings.

Diet and Nutrition in Gynecological Disorders: A Focus on Clinical Studies

A healthy lifestyle and a balanced diet play a paramount role in promoting and maintaining homeostatic functions and preventing an array of chronic and debilitating diseases. Based upon observational and epidemiological investigations, it is clear that nutritional factors and dietary habits play a significant role in gynecological disease development, including uterine leiomyoma, endometriosis, polycystic ovary syndrome, and gynecological malignancies. Diets rich in fruits and vegetables, Mediterranean diets, green tea, vitamin D, and plant-derived natural compounds may have a long-term positive impact on gynecological diseases, while fats, red meat, alcohol, and coffee may contribute to their development. Data regarding the association between dietary habits and gynecological disorders are, at times, conflicting, with potential confounding factors, including food pollutants, reduced physical activity, ethnic background, and environmental factors limiting overall conclusions. This review provides a synopsis of the current clinical data and biological basis of the association between available dietary and nutritional data, along with their impact on the biology and pathophysiology of different gynecological disorders, as well as an outlook on future directions that will guide further investigational research.

Pharmacological and non-pharmacological strategies for obese women with subfertility

BACKGROUND

Clinicians primarily recommend weight loss for obese women seeking pregnancy. The effectiveness of interventions aimed at weight loss in obese women with subfertility is unclear.

OBJECTIVES

To assess the effectiveness and safety of pharmacological and non-pharmacological strategies compared with each other, placebo, or no treatment for achieving weight loss in obese women with subfertility.

SEARCH METHODS

We searched the CGF Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, and AMED from inception to 18 August 2020. We also checked reference lists and contacted experts in the field for additional relevant papers.

SELECTION CRITERIA

We included published and unpublished randomised controlled trials in which weight loss was the main goal of the intervention. Our primary effectiveness outcomes were live birth or ongoing pregnancy and primary safety outcomes were miscarriage and adverse events. Secondary outcomes included clinical pregnancy, weight change, quality of life, and mental health outcome.

DATA COLLECTION AND ANALYSIS

Review authors followed standard Cochrane methodology.

MAIN RESULTS

This review includes 10 trials. Evidence was of very low to low quality: the main limitations were due to lack of studies and poor reporting of study methods. The main reasons for downgrading evidence were lack of details by which to judge risk of bias (randomisation and allocation concealment), lack of blinding, and imprecision. Non-pharmacological intervention versus no intervention or placebo Evidence is insufficient to determine whether a diet or lifestyle intervention compared to no intervention affects live birth (odds ratio (OR) 0.85, 95% confidence interval (CI) 0.65 to 1.11; 918 women, 3 studies; I² = 78%; low-quality evidence). This suggests that if the chance of live birth following no intervention is assumed to be 43%, the chance following diet or lifestyle changes would be 33% to 46%. We are uncertain if lifestyle change compared with no intervention affects miscarriage rate (OR 1.54, 95% CI 0.99 to 2.39; 917 women, 3 studies; I² = 0%; very low-quality evidence). Evidence is insufficient to determine whether lifestyle change compared with no intervention affects clinical pregnancy (OR 1.06, 95% CI 0.81 to 1.40; 917 women, 3 studies; I² = 73%; low-quality evidence). Lifestyle intervention resulted in a decrease in body mass index (BMI), but data were not pooled due to heterogeneity in effect (mean difference (MD) -3.70, 95% CI -4.10 to -3.30; 305 women, 1 study; low-quality evidence; and MD -1.80, 95% CI -2.67 to -0.93; 43 women, 1 study; very low-quality evidence). Non-pharmacological versus non-pharmacological intervention We are uncertain whether intensive weight loss interventions compared to standard care nutrition counselling affects live birth (OR 11.00, 95% CI 0.43 to 284; 11 women, 1 study; very low-quality evidence), clinical pregnancy (OR 11.00, 95% CI 0.43 to 284; 11 women, 1 study; very low-quality evidence), BMI (MD -3.00, 95% CI -5.37 to -0.63; 11 women, 1 study; very low-quality evidence), weight change (MD -9.00, 95% CI -15.50 to -2.50; 11 women, 1 study; very low-quality evidence), quality of life (MD 0.06, 95% CI -0.03 to 0.15; 11 women, 1 study; very low-quality evidence), or mental health (MD -7.00, 95% CI -13.92 to -0.08; 11 women, 1 study; very low-quality evidence). No study reported on adverse events . Pharmacological versus pharmacological intervention For metformin plus liraglutide compared to metformin we are uncertain of an effect on the adverse events nausea (OR 7.22, 95% CI 0.72 to 72.7; 28 women, 1 study; very low-quality evidence), diarrhoea (OR 0.31, 95% CI 0.01 to 8.3; 28 women, 1 study; very low-quality evidence), and headache (OR 5.80, 95% CI 0.25 to 133; 28 women, 1 study; very low-quality evidence). We are uncertain if a combination of metformin plus liraglutide vs metformin affects BMI (MD 2.1, 95% CI -0.42 to 2.62; 28 women, 1 study; very low-quality evidence) and total body fat (MD -0.50, 95% CI -4.65 to 3.65; 28 women, 1 study; very low-quality evidence). For metformin, clomiphene, and L-carnitine versus metformin, clomiphene, and placebo, we are uncertain of an effect on miscarriage (OR 3.58, 95% CI 0.73 to 17.55; 274 women, 1 study; very low-quality evidence), clinical pregnancy (OR 5.56, 95% CI 2.57 to 12.02; 274 women, 1 study; very low-quality evidence) or BMI (MD -0.3, 95% CI 1.17 to 0.57, 274 women, 1 study, very low-quality evidence). We are uncertain if dexfenfluramine versus placebo affects weight loss in kilograms (MD -0.10, 95% CI -2.77 to 2.57; 21 women, 1 study; very low-quality evidence). No study reported on live birth, quality of life, or mental health outcomes. Pharmacological intervention versus no intervention or placebo We are uncertain if metformin compared with placebo affects live birth (OR 1.57, 95% CI 0.44 to 5.57; 65 women, 1 study; very low-quality evidence). This suggests that if the chance of live birth following placebo is assumed to be 15%, the chance following metformin would be 7% to 50%. We are uncertain if metformin compared with placebo affects gastrointestinal adverse events (OR 0.91, 95% CI 0.32 to 2.57; 65 women, 1 study; very low-quality evidence) or miscarriage (OR 0.50, 95% CI 0.04 to 5.80; 65 women, 1 study; very low-quality evidence) or clinical pregnancy (OR 2.67, 95% CI 0.90 to 7.93; 96 women, 2 studies; I² = 48%; very low-quality evidence). We are also uncertain if diet combined with metformin versus diet and placebo affects BMI (MD -0.30, 95% CI -2.16 to 1.56; 143 women, 1 study; very low-quality evidence) or waist-to-hip ratio (WHR) (MD 2.00, 95% CI -2.21 to 6.21; 143 women, 1 study; very low-quality evidence). Pharmacological versus non-pharmacological intervention No study undertook this comparison.

AUTHORS' CONCLUSIONS

Evidence is insufficient to support the use of pharmacological and non-pharmacological strategies for obese women with subfertility. No data are available for the comparison of pharmacological versus non-pharmacological strategies. We are uncertain whether pharmacological or non-pharmacological strategies effect live birth, ongoing pregnancy, adverse events, clinical pregnancy, quality of life, or mental heath outcomes. However, for obese women with subfertility, a lifestyle intervention may reduce BMI. Future studies should compare a combination of pharmacological and lifestyle interventions for obese women with subfertility.

Vegan dietary pattern for the primary and secondary prevention of cardiovascular diseases

BACKGROUND

Diet plays a major role in the aetiology of cardiovascular disease (CVD) and as a modifiable risk factor is the focus of many prevention strategies. Recently vegan diets have gained popularity and there is a need to synthesise existing clinical trial evidence for their potential in CVD prevention.

OBJECTIVES

To determine the effectiveness of following a vegan dietary pattern for the primary and secondary prevention of CVD.

SEARCH METHODS

We searched the following electronic databases on 4 February 2020: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and Web of Science Core Collection. We also searched ClinicalTrials.gov in January 2021. We applied no language restrictions.

SELECTION CRITERIA

We selected randomised controlled trials (RCTs) in healthy adults and adults at high risk of CVD (primary prevention) and those with established CVD (secondary prevention). A vegan dietary pattern excludes meat, fish, eggs, dairy and honey; the intervention could be dietary advice, provision of relevant foods, or both. The comparison group received either no intervention, minimal intervention, or another dietary intervention. Outcomes included clinical events and CVD risk factors. We included only studies with follow-up periods of 12 weeks or more, defined as the intervention period plus post-intervention follow-up.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed studies for inclusion, extracted data and assessed risks of bias. We used GRADE to assess the certainty of the evidence. We conducted three main comparisons: 1. Vegan dietary intervention versus no intervention or minimal intervention for primary prevention; 2. Vegan dietary intervention versus another dietary intervention for primary prevention; 3. Vegan dietary intervention versus another dietary intervention for secondary prevention.

MAIN RESULTS

Thirteen RCTs (38 papers, 7 trial registrations) and eight ongoing trials met our inclusion criteria. Most trials contributed to primary prevention: comparisons 1 (four trials, 466 participants randomised) and comparison 2 (eight trials, 409 participants randomised). We included only one secondary prevention trial for comparison 3 (63 participants randomised). None of the trials reported on clinical endpoints. Other primary outcomes included lipid levels and blood pressure. For comparison 1 there was moderate-certainty evidence from four trials with 449 participants that a vegan diet probably led to a small reduction in total cholesterol (mean difference (MD) -0.24 mmol/L, 95% confidence interval (CI) -0.36 to -0.12) and low-density lipoprotein (LDL) cholesterol (MD -0.22 mmol/L, 95% CI -0.32 to -0.11), a very small decrease in high-density lipoprotein (HDL) levels (MD -0.08 mmol/L, 95% CI -0.11 to -0.04) and a very small increase in triglyceride levels (MD 0.11 mmol/L, 95% CI 0.01 to 0.21). The very small changes in HDL and triglyceride levels are in the opposite direction to that expected. There was a lack of evidence for an effect with the vegan dietary intervention on systolic blood pressure (MD 0.94 mmHg, 95% CI -1.18 to 3.06; 3 trials, 374 participants) and diastolic blood pressure (MD -0.27 mmHg, 95% CI -1.67 to 1.12; 3 trials, 372 participants) (low-certainty evidence). For comparison 2 there was a lack of evidence for an effect of the vegan dietary intervention on total cholesterol levels (MD -0.04 mmol/L, 95% CI -0.28 to 0.20; 4 trials, 163 participants; low-certainty evidence). There was probably little or no effect of the vegan dietary intervention on LDL (MD -0.05 mmol/L, 95% CI -0.21 to 0.11; 4 trials, 244 participants) or HDL cholesterol levels (MD -0.01 mmol/L, 95% CI -0.08 to 0.05; 5 trials, 256 participants) or triglycerides (MD 0.21 mmol/L, 95% CI -0.07 to 0.49; 5 trials, 256 participants) compared to other dietary interventions (moderate-certainty evidence). We are very uncertain about any effect of the vegan dietary intervention on systolic blood pressure (MD 0.02 mmHg, 95% CI -3.59 to 3.62)  or diastolic blood pressure (MD 0.63 mmHg, 95% CI -1.54 to 2.80; 5 trials, 247 participants (very low-certainty evidence)). Only one trial (63 participants) contributed to comparison 3, where there was a lack of evidence for an effect of the vegan dietary intervention on lipid levels or blood pressure compared to other dietary interventions (low- or very low-certainty evidence). Four trials reported on adverse events, which were absent or minor.

AUTHORS' CONCLUSIONS

Studies were generally small with few participants contributing to each comparison group. None of the included studies report on CVD clinical events. There is currently insufficient information to draw conclusions about the effects of vegan dietary interventions on CVD risk factors. The eight ongoing studies identified will add to the evidence base, with all eight reporting on primary prevention. There is a paucity of evidence for secondary prevention.

Effects of Dietary Glycemic Index and Glycemic Load on Cardiometabolic and Reproductive Profiles in Women with Polycystic Ovary Syndrome: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Women with polycystic ovary syndrome (PCOS) exhibit cardiometabolic (e.g., insulin resistance) and associated reproductive disruptions. Lifestyle modification (e.g., diet) is recommended as the first-line therapy to manage PCOS; however, a favorable dietary regimen remains unclear beyond energy restriction. We conducted a systematic review and meta-analysis of randomized controlled trials (RCTs) to summarize evidence on impacts of dietary glycemic index (GI) or glycemic load (GL) on cardiometabolic and reproductive profiles to update the International Evidence-based Guideline for the Assessment and Management of PCOS. Databases of MEDLINE, Cochrane, Web of Science, and Scopus were searched through 30 October 2019, and confirmed on 25 March 2020, to identify RCTs (≥8 wk) comparing the effects of diets with lower (LGI/LGL) and higher (HGI/HGL) GI/GL on glucoregulatory outcomes, lipid profile, anthropometrics, and androgen status in PCOS. The primary outcome was HOMA-IR. Data were pooled by random-effects models and expressed as weighted mean differences and 95% CIs. The risk of bias was assessed by the Cochrane tool. Ten RCTs (n = 403) were eligible. Eight evaluated LGI and 2 LGL diets. LGI diets decreased HOMA-IR (-0.78; -1.20, -0.37; I2 = 86.6%), fasting insulin (-2.39; -4.78, 0.00 μIU/mL; I2 = 76.8%), total cholesterol (-11.13; -18.23, -4.04 mg/dL; I2 = 0.0%), LDL cholesterol (-6.27; -12.01, -0.53 mg/dL; I2 = 0.0%), triglycerides (-14.85; -28.75, -0.95 mg/dL; I2 = 31.0%), waist circumference (-2.81; -4.40, -1.23 cm; I2 = 53.9%), and total testosterone (-0.21; -0.32, -0.09 nmol/L; I2 = 8.6%) compared with HGI diets (all: P ≤ 0.05) without affecting fasting glucose, HDL cholesterol, weight, or free androgen index (all: P ≥ 0.07). Some results were contradictory and only described narratively for 2 RCTs that evaluated LGL diets, since inclusion in meta-analyses was not possible. LGI diets improved glucoregulatory outcomes (HOMA-IR, insulin), lipid profiles, abdominal adiposity, and androgen status, conceivably supporting their inclusion for dietary management of PCOS. Further RCTs should confirm these observations and address whether LGI diets improve more patient-pressing complications, including ovulatory cyclicity, infertility, and cardiovascular disease risk in this high-risk population. This review was registered at www.crd.york.ac.uk/PROSPERO as CRD42020175300.

Using Social Media to Understand Online Social Factors Concerning Obesity: A Systematic Review (Preprint)

Background

Evidence in the literature surrounding obesity suggests that social factors play a substantial role in the spread of obesity. Although social ties with a friend who is obese increase the probability of becoming obese, the role of social media in this dynamic remains underexplored in obesity research. Given the rapid proliferation of social media in recent years, individuals socialize through social media and share their health-related daily routines, including dieting and exercising. Thus, it is timely and imperative to review previous studies focused on social factors in social media and obesity.

Objective

This study aims to examine web-based social factors in relation to obesity research.

Methods

We conducted a systematic review. We searched PubMed, Association for Computing Machinery, and ScienceDirect for articles published by July 5, 2019. Web-based social factors that are related to obesity behaviors were studied and analyzed.

Results

In total, 1608 studies were identified from the selected databases. Of these 1608 studies, 50 (3.11%) studies met the eligibility criteria. In total, 10 types of web-based social factors were identified, and a socioecological model was adopted to explain their potential impact on an individual from varying levels of web-based social structure to social media users’ connection to the real world.

Conclusions

We found 4 levels of interaction in social media. Gender was the only factor found at the individual level, and it affects user’s web-based obesity-related behaviors. Social support was the predominant factor identified, which benefits users in their weight loss journey at the interpersonal level. Some factors, such as stigma were also found to be associated with a healthy web-based social environment. Understanding the effectiveness of these factors is essential to help users create and maintain a healthy lifestyle.

Effectiveness of Non-Pharmacological Interventions for Overweight or Obese Infertile Women: A Systematic Review and Meta-Analysis

Obesity is a well-known risk factor for infertility, and nonpharmacological treatments are recommended as effective and safe, but evidence is still lacking on whether nonpharmacological interventions improve fertility in overweight or obese women. The aim of this study was to systematically assess the current evidence in the literature and to evaluate the impact of nonpharmacological interventions on improving pregnancy-related outcomes in overweight or obese infertile women. Seven databases were searched for randomized controlled trials (RCTs) of nonpharmacological interventions for infertile women with overweight or obesity through August 16, 2019 with no language restriction. A meta-analysis was conducted of the primary outcomes. A total of 21 RCTs were selected and systematically reviewed. Compared to the control group, nonpharmacological interventions significantly increased the pregnancy rate (relative risk (RR), 1.37; 95% CI, 1.04–1.81; p = 0.03; I² = 58%; nine RCTs) and the natural conception rate (RR, 2.17, 95% CI, 1.41–3.34; p = 0.0004; I² = 19%, five RCTs). However, they had no significant effect on the live birth rate (RR, 1.36, 95% CI, 0.94–1.95; p=0.10, I² = 65%, eight RCTs) and increased the risk of miscarriage (RR: 1.57, 95% CI, 1.05–2.36; p = 0.03; I² = 0%). Therefore, nonpharmacological interventions could have a positive effect on the pregnancy and natural conception rates, whereas it is unclear whether they improve the live birth rate. Further research is needed to demonstrate the integrated effects of nonpharmacological interventions involving psychological outcomes, as well as pregnancy-related outcomes.

Lifestyle Interventions for Polycystic Ovary Syndrome: Cross-Sectional Survey to Assess Women's Treatment and Outcome Preferences

Background

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of reproductive age. Diet and lifestyle programs improve health, but women’s preferences for these programs have not been formally explored.

Objective

The aim of our study was to examine diet and lifestyle program preferences among women with PCOS.

Methods

We conducted a cross-sectional online survey of women with PCOS.

Results

At least half of the 197 respondents expressed strong interest in programs addressing energy level, anxiety, depression, weight, diabetes prevention, menstrual period regulation, and hirsutism. Similarly, at least half reported willingness to modify their sleep, stress, and physical activity; and slightly less than half reported willingness to adopt a very low-carbohydrate, paleo, or low–glycemic index diet. At least half reported interest in online or mobile programs and email-based mentoring. Younger age was associated with interest in help with acne and fertility; higher body mass index was associated with wanting help with weight loss, energy, and anxiety; and greater stress eating was associated with wanting help with depression, anxiety, and menstrual period regulation.

Conclusions

To our knowledge, this is the first study to examine attitudes and preferences of women with PCOS toward such programs. Future online and mobile diet and lifestyle programs may be able to capitalize on this information to better target this population’s expressed preferences.

Implementing the international evidence-based guideline of assessment and management of polycystic ovary syndrome (PCOS): how to achieve weight loss in overweight and obese women with PCOS?

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women. Many of these women are overweight or obese. A minor weight loss of 5%-10% can significantly reduce reproductive, metabolic and psychological symptoms of PCOS and is recommended as a first step in the treatment of overweight or obese women with PCOS. Many weight loss programs have been proposed, but optimal methods on how to achieve the recommend weight loss are lacking. The aim of this systematic review was to generate practical tools for health professionals to guide women with PCOS towards a sustainable healthier lifestyle. PRISMA guidelines were used to conduct the systematic review. Eleven randomized controlled trials were found eligible for inclusion. Lifestyle modification strategies consisted of a diet, physical exercise, behavioural coaching or combined interventions. Mean weight loss ranged from +0.5 to -10.6 % of the initial body weight. However, the majority of the studies reported considerable drop-out rates varying between 12% and 47%. The heterogeneity of the described interventions and the high drop-out rates impede extrapolation of these results to daily clinical care. Hence, none of the described interventions seems superior to another in achieving substantial weight loss. In conclusion, the need for obtaining a healthier weight in overweight and obese women with PCOS is now well accepted. However, achieving this goal remains a challenge for both patients and healthcare providers. More research focusing on the multidisciplinary approach of lifestyle modification advice in daily practice is needed.

Adherence to treatment for polycystic ovarian syndrome: A systematic review

Background

Polycystic ovarian syndrome (PCOS) is one of the most prevalent endocrine disorders of women of reproductive age. Treatment plans for this chronic condition frequently include long-term use of a combination of medication and lifestyle interventions. However, treatment outcomes are dependent on adherence to treatment regimens. This study aimed to systematically review the literature for reported adherence to treatments for PCOS.

Methods

A systematic search of Embase, Cochrane, PubMed, CINAHL, PsychINFO, SCOPUS, and International Pharmaceutical Abstracts from inception until January 2019 utilizing the terms PCOS, adherence, and patient compliance was conducted. A total of 179 possible articles were identified.

Results

Fourteen articles reporting adherence data were included in the review. Self-report was the most commonly reported method of measuring adherence. Adherence to lifestyle interventions, such as prescribed diets and physical activity, was reported in ten studies and adherence to medications was reported in seven studies, with some reporting both.

Conclusions

Minimal data are available regarding factors associated with adherence in patients with PCOS. Diverse methods of adherence assessment are utilized. Future studies of PCOS treatments should effectively assess and report adherence data as it is essential to evaluating the effectiveness of PCOS treatments and is critically needed to guide clinician efforts to facilitate optimal outcomes for patients.

The Potential for Plant-Based Diets to Promote Health Among Blacks Living in the United States

Plant-based diets are associated with reduced risks of various chronic diseases in the general population. However, it is unclear how these benefits translate to Blacks living in the United States, who are disproportionately burdened with heart disease, cancer, diabetes, obesity, and chronic kidney disease. The objectives of this study were to: (1) review the general evidence of plant-based diets and health outcomes; (2) discuss how this evidence translates to Blacks following a plant-based diet; and (3) provide recommendations and considerations for future studies in this area. Interestingly, although the evidence supporting plant-based diets in the general population is robust, little research has been done on Blacks specifically. However, the available data suggests that following a plant-based diet may reduce the risk of heart disease and possibly cancer in this population. More research is needed on cardiovascular disease risk factors, cancer subtypes, and other chronic diseases. Further, attention must be given to the unique individual, familial, communal, and environmental needs that Blacks who follow plant-based diets may have. Interventions must be culturally appropriate in order to achieve long-term success, and providing low-cost, flavorful, and nutritious options will be important.

The effects of plant-based diets on the body and the brain: a systematic review

Western societies notice an increasing interest in plant-based eating patterns such as vegetarian and vegan, yet potential effects on the body and brain are a matter of debate. Therefore, we systematically reviewed existing human interventional studies on putative effects of a plant-based diet on the metabolism and cognition, and what is known about the underlying mechanisms. Using the search terms "plant-based OR vegan OR vegetarian AND diet AND intervention" in PubMed filtered for clinical trials in humans retrieved 205 studies out of which 27, plus an additional search extending the selection to another five studies, were eligible for inclusion based on three independent ratings. We found robust evidence for short- to moderate-term beneficial effects of plant-based diets versus conventional diets (duration ≤ 24 months) on weight status, energy metabolism and systemic inflammation in healthy participants, obese and type-2 diabetes patients. Initial experimental studies proposed novel microbiome-related pathways, by which plant-based diets modulate the gut microbiome towards a favorable diversity of bacteria species, yet a functional "bottom up" signaling of plant-based diet-induced microbial changes remains highly speculative. In addition, little is known, based on interventional studies about cognitive effects linked to plant-based diets. Thus, a causal impact of plant-based diets on cognitive functions, mental and neurological health and respective underlying mechanisms has yet to be demonstrated. In sum, the increasing interest for plant-based diets raises the opportunity for developing novel preventive and therapeutic strategies against obesity, eating disorders and related comorbidities. Still, putative effects of plant-based diets on brain health and cognitive functions as well as the underlying mechanisms remain largely unexplored and new studies need to address these questions.

Lifestyle changes in women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) affects 8% to 13% of reproductive-aged women and is associated with reproductive and metabolic dysfunction. Obesity worsens the presentation of PCOS and weight management (weight loss, maintenance or prevention of excess weight gain) is proposed as an initial treatment strategy, best achieved through lifestyle changes incorporating diet, exercise and behavioural interventions.

OBJECTIVES

To assess the effectiveness of lifestyle treatment in improving reproductive, anthropometric (weight and body composition), metabolic and quality of life factors in PCOS.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, PsycINFO, CINAHL and AMED (date of last search March 2018). We also searched controlled trials registries, conference abstracts, relevant journals, reference lists of relevant papers and reviews, and grey literature databases, with no language restrictions applied.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing lifestyle treatment (diet, exercise, behavioural or combined treatments) to minimal or no treatment in women with PCOS.

DATA COLLECTION AND ANALYSIS

Two authors independently selected trials, assessed evidence quality and risk of bias, and extracted data. Our primary outcomes were live birth, miscarriage and pregnancy. We used inverse variance and fixed-effect models in the meta-analyses. We reported dichotomous outcomes as an odds ratio and continuous outcomes as a mean difference (MD) or standardised mean difference (SMD).

MAIN RESULTS

We included 15 studies with 498 participants. Ten studies compared physical activity to minimal dietary and behavioural intervention or no intervention. Five studies compared combined dietary, exercise and behavioural intervention to minimal intervention. One study compared behavioural intervention to minimal intervention. Risk of bias varied: eight studies had adequate sequence generation, seven had adequate clinician or outcome assessor blinding, seven had adequate allocation concealment, six had complete outcome data and six were free of selective reporting. No studies assessed the fertility primary outcomes of live birth or miscarriage. No studies reported the secondary reproductive outcome of menstrual regularity, as defined in this review.Lifestyle intervention may improve a secondary (endocrine) reproductive outcome, the free androgen index (FAI) (MD -1.11, 95% confidence interval (CI) -1.96 to -0.26, 6 RCTs, N = 204, I2 = 71%, low-quality evidence). Lifestyle intervention may reduce weight (kg) (MD -1.68 kg, 95% CI -2.66 to -0.70, 9 RCTs, N = 353, I2 = 47%, low-quality evidence). Lifestyle intervention may reduce body mass index (BMI) (kg/m2) (-0.34 kg/m2, 95% CI -0.68 to -0.01, 12 RCTs, N = 434, I2= 0%, low-quality evidence). We are uncertain of the effect of lifestyle intervention on glucose tolerance (glucose outcomes in oral glucose tolerance test) (mmol/L/minute) (SMD -0.02, 95% CI -0.38 to 0.33, 3 RCTs, N = 121, I2 = 0%, low-quality evidence).

AUTHORS' CONCLUSIONS

Lifestyle intervention may improve the free androgen index (FAI), weight and BMI in women with PCOS. We are uncertain of the effect of lifestyle intervention on glucose tolerance. There were no studies that looked at the effect of lifestyle intervention on live birth, miscarriage or menstrual regularity. Most studies in this review were of low quality mainly due to high or unclear risk of bias across most domains and high heterogeneity for the FAI outcome.

Exercise, or exercise and diet for the management of polycystic ovary syndrome: a systematic review and meta-analysis

BACKGROUND

Typically, management of PCOS focuses on lifestyle changes (exercise and diet), aiming to alleviate symptoms, and lower the associated risk of type 2 diabetes and cardiovascular disease. Our objective was to analyse evidence on the effectiveness of exercise in the management of PCOS, when compared to (i) usual care, (ii) diet alone, and (iii) exercise combined with diet, and also exercise combined with diet, compared to (i) control or usual care and (ii) diet alone.

METHODS

Relevant databases were searched (June 2017) with no time limit for trial inclusion. Eligible trials employed a randomised or quasi-randomised design to measure the chronic effects of exercise, or exercise and diet in women with PCOS.

RESULTS

Searches returned 2390 articles; of those, 27 papers from 18 trials were included. Results are presented as mean difference (MD) and 95% confidence intervals (95% CI). Compared with control, exercise had a statistical effect on change from baseline fasting insulin (MD - 2.44 μIU/mL, 95% CIs - 4.24 to - 0.64; very low-quality evidence), HOMA-IR (- 0.57, - 0.99 to - 0.14; very low-quality evidence), total cholesterol (- 5.88 mg/dL, - 9.92 to - 1.83; low-quality evidence), LDL cholesterol (- 7.39 mg/dL, - 9.83 to - 4.95; low-quality evidence), and triglycerides (- 4.78 mg/dL, - 7.52 to - 2.05; low-quality evidence). Exercise also improved VO2 max (3.84 ml/kg/min, 2.87 to 4.81), waist circumference (- 2.62 cm, - 4.13 to - 1.11), and body fat percentage (- 1.39%, - 2.61 to - 0.18) when compared with usual care. No effect was found for change value systolic/diastolic blood pressure, fasting glucose, HDL cholesterol (all low-quality evidence), or waist-to-hip ratio. Many favourable change score findings were supported by post-intervention value analyses: fasting insulin (- 2.11 μIU/mL, - 3.49 to - 0.73), total cholesterol (- 6.66 mg/dL, - 11.14 to - 2.17), LDL cholesterol (- 6.91 mg/dL, - 12.02 to - 1.80), and VO2 max (5.01 ml/kg/min, 3.48 to 6.54). Statistically lower BMI (- 1.02 kg/m2, - 1.81 to - 0.23) and resting heart rate (- 3.26 beats/min - 4.93 to - 1.59) were also revealed in post-intervention analysis. Subgroup analyses revealed the greatest improvements in overweight/obese participants, and more outcomes improved when interventions were supervised, aerobic in nature, or of a shorter duration. Based on limited data, we found no differences for any outcome between the effects of exercise and diet combined, and diet alone. It was not possible to compare exercise vs diet or exercise and diet combined vs diet.

CONCLUSION

Statistically beneficial effects of exercise were found for a range of metabolic, anthropometric, and cardiorespiratory fitness-related outcomes. However, caution should be adopted when interpreting these findings since many outcomes present modest effects and wide CIs, and statistical effects in many analyses are sensitive to the addition/removal of individual trials. Future work should focus on rigorously designed, well-reported trials that make comparisons involving both exercise and diet.

SYSTEMATIC REVIEW REGISTRATION

This systematic review was prospectively registered on the Prospero International Prospective Register of Systematic Reviews ( CRD42017062576 ).

A Comparison of a Pulse-Based Diet and the Therapeutic Lifestyle Changes Diet in Combination with Exercise and Health Counselling on the Cardio-Metabolic Risk Profile in Women with Polycystic Ovary Syndrome: A Randomized Controlled Trial

We compared the effects of a low-glycemic index pulse-based diet, containing lentils, beans, split peas, and chickpeas, to the Therapeutic Lifestyle Changes (TLC) diet on cardio-metabolic measures in women with polycystic ovary syndrome (PCOS). Ninety-five women (18⁻35 years) enrolled in a 16-week intervention; 30 women in the pulse-based and 31 in the TLC groups completed the study. Women participated in aerobic exercise training (minimum 5 days/week for 45 min/day) and were counselled (monthly) about PCOS and lifestyle modification. Women underwent longitudinal follow-up post-intervention. The pulse-based group had a greater reduction in total area under the curve for insulin response to a 75-g oral glucose tolerance test (mean change ± SD: -121.0 ± 229.9 vs. -27.4 ± 110.2 µIU/mL × min; p = 0.05); diastolic blood pressure (-3.6 ± 6.7 vs. -0.2 ± 6.7 mmHg, p = 0.05); triglyceride (-0.2 ± 0.6 vs. 0.0 ± 0.5 mmol/L, p = 0.04); low-density lipoprotein cholesterol (-0.2 ± 0.4 vs. -0.1 ± 0.4 mmol/L, p = 0.05); total cholesterol/high-density lipoprotein cholesterol (TC/HDL-C; -0.4 ± 0.4 vs. 0.1 ± 0.4, p < 0.001); and a greater increase in HDL-C (0.1 ± 0.2 vs. -0.1 ± 0.2 mmol/L, p < 0.01) than the TLC group. Decreased TC/HDL-C (p = 0.02) at six-month and increased HDL-C and decreased TC/HDL-C (p ≤ 0.02) at 12-month post-intervention were maintained in the pulse-based group. A pulse-based diet may be more effective than the TLC diet at improving cardio-metabolic disease risk factors in women with PCOS.

TRIAL REGISTRATION

CinicalTrials.gov identifier, NCT01288638.

The Efficacy of 24-Month Metformin for Improving Menses, Hormones, and Metabolic Profiles in Polycystic Ovary Syndrome

CONTEXT

The long-term effects of metformin in women with polycystic ovarian syndrome (PCOS) are inadequately studied.

OBJECTIVE

The effects of metformin on women with PCOS during 24 months with respect to menses, hormones, and metabolic profiles are assessed.

DESIGN

Prospective cohort.

SETTING

A reproductive endocrinology clinic in a university-affiliated medical center.

PATIENTS

One hundred nineteen women with PCOS, defined by the Rotterdam criteria, were enrolled.

INTERVENTION

Metformin was given daily for 24 months.

MAIN OUTCOME MEASURES

The primary outcome was the proportion of patients with regular menstruation during treatment. Changes in anthropometric, hormonal, and metabolic parameters were also assessed. Analyses were performed using segmented regression analysis with a generalized estimating equation methodology. Outcomes are expressed as magnitude of change from the baseline.

RESULTS

Both overweight (OW) and normal-weight (NW) women with PCOS had increased menstrual frequency and decreased body mass index (BMI), testosterone, and luteinizing hormone levels in the first 6 months. Further stratification showed that NW women exhibiting elevated testosterone at baseline had the largest magnitude of improvement at 6 months [odds ratio (OR), 7.21; 95% confidence interval (CI), 2.35 to 22.17], whereas OW patients with normal testosterone were most likely to achieve normal menses at 12 months (OR, 0.63; 95% CI, 0.47 to 0.77).

CONCLUSIONS

Metformin was associated with improvements in the menstrual cycle and most hormonal profiles in OW and NW women with PCOS during 24 months of treatment. Most parameters reached maximal response and steady-state after 6 months. Phenotypic differences in baseline BMI and testosterone level can be used as patient selection criteria or treatment prognostics.

A randomized controlled trial to prevent excessive gestational weight gain and promote postpartum weight loss in overweight and obese women: Health In Pregnancy and Postpartum (HIPP)

BACKGROUND

Interventions to prevent excessive gestational weight gain and promote postpartum weight loss have yielded modest results, particularly in overweight and obese women.

OBJECTIVES

To examine the impact of a theory-based lifestyle intervention on gestational weight gain, postpartum weight loss, and related maternal and child outcomes and to examine race differences in these outcomes.

DESIGN

A randomized controlled trial (target N=400; 200 intervention, 200 standard care; 200 African American, 200 white).

METHODS

Overweight and obese African American and white women ≤16weeks gestation are recruited from obstetrics and gynecology clinics in South Carolina. Intervention participants receive two in-depth counseling sessions (early pregnancy and postpartum), telephone counseling, behavioral podcasts, and social media support that target weight self-monitoring and increasing physical activity and healthy dietary behavior practices, guided by Social Cognitive Theory. Standard care participants receive monthly mailings and a matched number of podcasts on non-weight related topics. All intervention activities last from ≤18weeks gestation to 6months after delivery. Gestational weight gain is the primary outcome. Secondary outcomes are meeting gestational weight gain guidelines (inadequate, adequate, excessive), weekly rate of gestational weight gain, postpartum weight retention, physical activity and dietary behaviors, health-related quality of life, and offspring adiposity. Participants are assessed at baseline (≤16weeks gestation), 32weeks gestation, and 6 and 12months postpartum, and offspring are assessed at 6 and 12months.

SUMMARY

HIPP is an innovative study that addresses significant gaps in the literature. Primary outcome results are expected in 2019.

Peer-Based Social Media Features in Behavior Change Interventions: Systematic Review

Background

Incorporating social media features into digital behavior change interventions (DBCIs) has the potential to contribute positively to their success. However, the lack of clear design principles to describe and guide the use of these features in behavioral interventions limits cross-study comparisons of their uses and effects.

Objective

The aim of this study was to provide a systematic review of DBCIs targeting modifiable behavioral risk factors that have included social media features as part of their intervention infrastructure. A taxonomy of social media features is presented to inform the development, description, and evaluation of behavioral interventions.

Methods

Search terms were used in 8 databases to identify DBCIs that incorporated social media features and targeted tobacco smoking, diet and nutrition, physical activities, or alcohol consumption. The screening and review process was performed by 2 independent researchers.

Results

A total of 5264 articles were screened, and 143 articles describing a total of 134 studies were retained for full review. The majority of studies (70%) reported positive outcomes, followed by 28% finding no effects with regard to their respective objectives and hypothesis, and 2% of the studies found that their interventions had negative outcomes. Few studies reported on the association between the inclusion of social media features and intervention effect. A taxonomy of social media features used in behavioral interventions has been presented with 36 social media features organized under 7 high-level categories. The taxonomy has been used to guide the analysis of this review.

Conclusions

Although social media features are commonly included in DBCIs, there is an acute lack of information with respect to their effect on outcomes and a lack of clear guidance to inform the selection process based on the features’ suitability for the different behaviors. The proposed taxonomy along with the set of recommendations included in this review will support future research aimed at isolating and reporting the effects of social media features on DBCIs, cross-study comparisons, and evaluations.

Users, Uses, and Effects of Social Media in Dietetic Practice: Scoping Review of the Quantitative and Qualitative Evidence

BACKGROUND

Social media platforms are increasingly used by registered dietitians (RDs) to improve knowledge translation and exchange in nutrition. However, a thorough understanding of social media in dietetic practice is lacking.

OBJECTIVE

The objective of this study was to map and summarize the evidence about the users, uses, and effects of social media in dietetic practice to identify gaps in the literature and inform future research by using a scoping review methodology.

METHODS

Stages for conducting the scoping review included the following: (1) identifying the research question; (2) identifying relevant studies through a comprehensive multidatabase and gray literature search strategy; (3) selecting eligible studies; (4) charting the data; and (5) collating, summarizing, and reporting results for dissemination. Finally, knowledge users (RDs working for dietetic professional associations and public health organizations) were involved in each review stage to generate practical findings.

RESULTS

Of the 47 included studies, 34 were intervention studies, 4 were descriptive studies, 2 were content analysis studies, and 7 were expert opinion papers in dietetic practice. Discussion forums were the most frequent social media platform evaluated (n=19), followed by blogs (n=13) and social networking sites (n=10). Most studies targeted overweight and obese or healthy users, with adult populations being most studied. Social media platforms were used to deliver content as part of larger multiple component interventions for weight management. Among intervention studies using a control group with no exposition to social media, we identified positive, neutral, and mixed effects of social media for outcomes related to users' health behaviors and status (eg, dietary intakes and body weight), participation rates, and professional knowledge. Factors associated with the characteristics of the specific social media, such as ease of use, a design for quick access to desired information, and concurrent reminders of use, were perceived as the main facilitators to the use of social media in dietetic practice, followed to a lesser extent by interactions with an RD and social support from fellow users. Barriers to social media use were mostly related to complicated access to the site and time issues.

CONCLUSIONS

Research on social media in dietetic practice is at its infancy, but it is growing fast. So far, this field of research has targeted few social media platforms, most of which were assessed in multiple-component interventions for weight management among overweight or obese adults. Trials isolating the effects and mechanisms of action of specific social media platforms are needed to draw conclusions regarding the effectiveness of those tools to support dietetic practice. Future studies should address barriers and facilitators related to the use of social media written by RDs and should explore how to make these tools useful for RDs to reach health consumers to improve health through diet.

The Use of Social Networking Sites (SNSs) in Health Communication Campaigns: Review and Recommendations

The past decade has witnessed a rapid increase in the use of Social Networking Sites (SNSs) in health communication campaigns seeking to achieve an ambitious range of health-related impacts. This article provides a review of 40 studies and research protocols, with a focus on two key factors that differentiate SNSs from more traditional health communication approaches of the past. The first is the potential dualism between message sender and receiver, in which receivers become receiver-sources who forward and amplify the content and reach of health messages. The second is the potential dualism between message and message impact, in which the act of forwarding and modifying messages by receiver-sources itself becomes a measure of message impact. Each of these dualisms has implications for the design and evaluation of contemporary health communication campaigns. The review concludes with a series of observations and recommendations for future health communication research.

Racial and ethnic minority enrollment in randomized clinical trials of behavioural weight loss utilizing technology: a systematic review

Many racial and ethnic minority groups (minorities) are disproportionately affected by overweight and obesity; however, minorities are often under-represented in clinical trials of behavioural weight loss (BWL) treatment, potentially limiting the generalizability of these trials' conclusions. Interventions involving technology may be particularly well suited to overcoming the barriers to minority enrollment in BWL trials, such as demanding or unpredictable work schedules, caregiving responsibilities and travel burdens. Thus, this systematic review aimed to describe minority enrollment in trials utilizing technology in interventions, as well as to identify which form(s) of technology yield the highest minority enrollment. Results indicated relatively low enrollment of minorities. Trials integrating smartphone use exhibited significantly greater racial minority enrollment than trials that did not; trials with both smartphone and in-person components exhibited the highest racial minority enrollment. This review is the first to explore how the inclusion of technology in BWL trials relates to minority enrollment and can help address the need to improve minority enrollment in weight loss research.

The role of a pulse-based diet on infertility measures and metabolic syndrome risk: protocol of a randomized clinical trial in women with polycystic ovary syndrome

Background

Polycystic Ovary Syndrome (PCOS) is an endocrine disorder in women of reproductive age with an estimated prevalence of 5–20% of premenopausal women. The clinical symptoms common to PCOS include menstrual dysfunction, hyperandrogenemia, hirsutism, polycystic ovaries, insulin resistance, and hyperinsulinemia. Women with PCOS are at an increased risk of infertility, obesity and type 2 diabetes mellitus. Insulin resistance and hyperinsulinemia are believed to be key contributing factors to the pathogenesis of PCOS; excessive amounts of insulin are directly associated with the increased ovarian production of androgens and metabolic features of PCOS. Pulse-based diets (e.g., beans, chickpeas) are associated with improved glycemic control and have insulin lowering effects. The purpose of this study is to determine whether a pulse-based diet is more effective than the diet recommended by the National Cholesterol Education Program. The primary outcomes of this study are disease measures related to PCOS, with secondary outcomes including measures related to metabolic syndrome.

Methods

Women with symptoms of PCOS will be recruited for the study and a diagnosis of PCOS will be determined by an obstetrician-gynecologist. Women with PCOS will be randomly assigned to receive either a pulse-based diet or the National Cholesterol Education Program therapeutic lifestyle changes (TLC) diet for 16 weeks while participating in an aerobic exercise program. One hundred participants will be required (drop-out rate of 32%) for recruitment to provide 80% power for detecting a significant difference in fasting glucose (p < 0.05). Measures related to infertility, metabolic syndrome, quality of life, dietary intake and physical activity will be assessed pre- and post-intervention with follow up assessment at 6- and 12-months post-intervention.

Discussion

Polycystic ovary syndrome is the most common endocrine disorder in women of reproductive age and there is currently no recommended diet for this population of women. The multidisciplinary nature of this study, including determination of measures related to metabolic syndrome, infertility and physical activity provide a comprehensive assessment of any benefits associated with a pulse-based diet in women with PCOS. The results of this study will help in providing evidence-based recommendations for the optimum diet to reduce symptoms associated with PCOS.

Trial registration

NCT01288638. Trial registered January 13, 2011.

Red Meat and Health

Despite its nutritional benefits, there is an increasing body of evidence to suggest that regular consumption of red meat may negatively impact health and disease risk, including the risk of most common chronic diseases. This chapter reviews the current evidence linking red and processed meat intakes with chronic disease, obesity and mortality risks and discusses possible mechanisms to explain these associations. Research on the health benefits of diets low in red meat, including vegetarian, vegan, Mediterranean and other plant-based diets, is also reviewed.

Red Meat and Health

Despite its nutritional benefits, there is an increasing body of evidence to suggest that regular consumption of red meat may negatively impact health and disease risk, including the risk of most common chronic diseases. This chapter reviews the current evidence linking red and processed meat intakes with chronic disease, obesity and mortality risks and discusses possible mechanisms to explain these associations. Research on the health benefits of diets low in red meat, including vegetarian, vegan, Mediterranean and other plant-based diets, is also reviewed.

Comparative effectiveness of plant-based diets for weight loss: a randomized controlled trial of five different diets

OBJECTIVE

The aim of this study was to determine the effect of plant-based diets on weight loss.

METHODS

Participants were enrolled in a 6-mo, five-arm, randomized controlled trial in 2013 in South Carolina. Participants attended weekly group meetings, with the exception of the omnivorous group, which served as the control and attended monthly meetings augmented with weekly e-mail lessons. All groups attended monthly meetings for the last 4 mo of the study. Diets did not emphasize caloric restriction.

RESULTS

Overweight adults (body mass index 25-49.9 kg/m(2); age 18-65 y, 19% non-white, and 27% men) were randomized to a low-fat, low-glycemic index diet: vegan (n = 12), vegetarian (n = 13), pesco-vegetarian (n = 13), semi-vegetarian (n = 13), or omnivorous (n = 12). Fifty (79%) participants completed the study. In intention-to-treat analysis, the linear trend for weight loss across the five groups was significant at both 2 (P < 0.01) and 6 mo (P < 0.01). At 6 mo, the weight loss in the vegan group (-7.5% ± 4.5%) was significantly different from the omnivorous (-3.1% ± 3.6%; P = 0.03), semi-vegetarian (-3.2% ± 3.8%; P = 0.03), and pesco-vegetarian (-3.2% ± 3.4%; P = 0.03) groups. Vegan participants decreased their fat and saturated fat more than the pesco-vegetarian, semi-vegetarian, and omnivorous groups at both 2 and 6 mo (P < 0.05).

CONCLUSIONS

Vegan diets may result in greater weight loss than more modest recommendations.

Key elements of plant-based diets associated with reduced risk of metabolic syndrome

Approximately 20 %-25 % of adults worldwide have metabolic syndrome. Vegetarian and vegan diets have demonstrated effectiveness in improving body weight, glycemic control, and cardiovascular risk factors, as compared with conventional therapeutic approaches, and are potentially useful in the prevention of metabolic syndrome. This article consists of two steps: (1) a review of the literature on studies examining vegetarian and vegan diets and metabolic syndrome and (2) a review of foods and nutrients that are protective against or associated with metabolic syndromes that may help to explain the beneficial effects of plant-based dietary approaches for metabolic syndrome. The present review found eight observational research studies, and no intervention studies, examining the association of plant-based dietary approaches with metabolic syndrome. These studies, conducted mostly in Asian populations, yielded varying results. The majority, however, found better metabolic risk factors and lowered risk of metabolic syndrome among individuals following plant-based diets, as compared with omnivores. Some dietary components that are lower in the diets of vegetarians, such as energy intake, saturated fat, heme iron, and red and processed meat, may influence metabolic syndrome risk. In addition, plant-based diets are higher in fruits, vegetables, and fiber, which are protective against the development of metabolic syndrome.